José-Antonio de la Peña, born in México in 1958, is a mathematician at the Universidad Autónoma de México. An expert in algebra, he has published around 150 papers and has received several honors, notably membership of El Colegio Nacional (México) since 2012.

• 1 Introduction and First Examples.- 2 A Categorical Approach.- 3 Constructive Methods.- 4 Spectral Methods in Representation Theory.- 5 Group Actions on Algebras and Module Categories.- 6 Reflections and Weyl Groups.- 7 Simply Connected Algebras.- 8 Degenerations of Algebras.- 9 Further Comments.

José-Antonio de la Peña, born in México in 1958, is a mathematician at the Universidad Autónoma de México. An expert in algebra, he has published around 150 papers and has received several honors, notably membership of El Colegio Nacional (México) since 2012.

• 1 Introduction and First Examples.- 2 A Categorical Approach.- 3 Constructive Methods.- 4 Spectral Methods in Representation Theory.- 5 Group Actions on Algebras and Module Categories.- 6 Reflections and Weyl Groups.- 7 Simply Connected Algebras.- 8 Degenerations of Algebras.- 9 Further Comments.

José-Antonio de la Peña, born in México in 1958, is a mathematician at the Universidad Autónoma de México. An expert in algebra, he has published around 150 papers and has received several honors, notably membership of El Colegio Nacional (México) since 2012.

• 1 Introduction and First Examples.- 2 A Categorical Approach.- 3 Constructive Methods.- 4 Spectral Methods in Representation Theory.- 5 Group Actions on Algebras and Module Categories.- 6 Reflections and Weyl Groups.- 7 Simply Connected Algebras.- 8 Degenerations of Algebras.- 9 Further Comments.